1. Field of the Invention
The invention relates to a rotary indexing machine for use in a group of machining stations, in whose machining zones is arranged in each case at least one tensioning device for exchangeable tool holders. Such a rotary indexing machine is described in the German Patent Specification DD 293 298 and in essence comprises a rotary indexing unit provided with a lift-and-turn device, on which are arranged support elements that are suitable for accepting the tool holders. The lift-and-turn device is designed such that, in each case, it can grasp under several tool holders when it is moved from a lowered position into a raised position. As soon as the tool holders have been lifted from their machining positions, a turning process of the turning device is begun, in order to bring the tool holders to their new machining positions. A subsequent set-down process then places the tool holders again onto the rotary indexing machines, which are provided with a tensioning device that works in conjunction with the workpiece holder, in order to fix the workpiece for the subsequent treatment process by machine.
2. Description of the Prior Art
The lift-and-turn device of the rotary indexing unit includes a piston rod; in the prior art, connected to the piston rod is a gearing that works in conjunction with a hydraulic cylinder in order to carry out the turning movement. Such a drive system is complex, since gearing and drive components must follow the lifting movement, which leads to an increase of the moved mass.